Home Recipes Dessert Brownies and Bars Monster Cookie Bars
by Jennifer Debth
8 Comments
5 from 2 votes
This post may contain affiliate links. Read our disclosure policy.
TheseMonster Cookie Barsare thick, chewy, ultra ooey-gooey, and packed with peanut butter, oats, M&Ms, and three types of chocolate!
Quick Navigation
- General
- What are monster cookies?
- Ingredients
- How to make
- Get the recipe
- Frequently Asked Questions
- What peanut butter to use
- What kind of oats to use
- Variations
- How to store
- Nutrition information
These monster cookie bars are essentially my monster cookie recipe made in bar form and letmetellyou, they’re SO delicious. Packed with oats, peanut butter, and YOUR favorite mix-ins…what’s not to love?!
What are monster cookie bars?
Monster cookie bars are essentially monster cookies, but instead of being portioned out into cookies, they’re baked in a baking dish and sliced into squares. Both monster cookie bars and classic monster cookies are hearty, soft, and chewy, and made with peanut butter, oats, and a variety of mix-ins such as M&Ms and chocolate chips.
Ingredients
These monster cookie bars use pantry staples that you likely have on hand already!
- Unsalted Butter– melted and beat together with the sugar for a soft, chewier texture and classic buttery taste.
- Dark Brown Sugar and Granulated Sugar– both add sweetness. The molasses in dark brown sugar also provides a soft, chewy texture and rich, caramel-y flavor.
- Peanut Butter– use your favorite processed peanut butter such as Jiff or Skippy. I use creamy peanut butter but feel free to use crunchy peanut butter for some added texture, if preferred.
- Egg– binds the cookie bars together so they can hold their shape.
- Vanilla Extract– adds flavor depth and a touch of warm sweetness.
- Old Fashioned Oats– gives the bars their structure and a hearty, chewy texture. You can try using quick oats, but they won’t be as thick and and may not hold up into bars well.
- Baking Soda– gives a little lift so the cookie bars aren’t too dense.
- Salt– balances out the sweetness while also bringing out other flavors in the cookie bars.
- M&Ms– a classic monster cookie mix-in that adds delicious melted chocolate creaminess and candy crunch.
- Other Mix-Ins– I used butterscotch chips, chocolate chunks, chocolate chips, and white chocolate chips.
Pro tip
Feel free to your YOUR favorite mix-ins! Raisins, craisins, chopped nuts, flavored baking chips, etc.
How to make
These monster cookie bars come together with just 15 minutes of prep!
- In the bowl of your stand mixer, beat together melted butter, brown sugar, and granulated sugar until fluffy.
- Beat in peanut butter, eggs, and vanilla until combined then add in oats, baking soda, salt, M&Ms, and additional mix-ins.
- Transfer the mixture to a greasedbaking dish lined with a parchment sling then use your hands to press the mixture into an even layer.
- Press in extra toppings, if desired, then bake at 350ºF for 30-40 minutes. Cool completely before removing from the pan, slicing, and serving!
Pro tip
Using a parchment paper sling allows you to easily lift the bars out of the pan before slicing and serving!
What peanut butter to use
Use a processed peanut butter such as Jiff or Skippy. I prefer to use creamy but crunchy would work as well!
Pro tip
Don’t use an all-natural peanut butter. The runnier, more oily texture can prevent the bars from holding their shape.
What kind of oats to use
Old-fashioned oats! Their hearty, chewy texture yields the best result. You canuse quick-cooking oats but they won’t be as sturdy.
Pro tip
Don’t use steel-cut oats — these oats are very hard and crunchy until cooked.
Variations
- Try other mix-ins.Try peanut butter chips, peanut M&Ms, toffee bits, nuts, dried fruits, etc.
- Use crunchy peanut butter.Swap the creamy peanut butter for crunchy for some extra texture.
- Make cookies.Check out my monster cookie recipe instead.
How to store
Leftover monster cookie bars will last for up to a week at room temperature, for up to 2 weeks in the fridge, or for up to 3 months in the freezer.
To enjoy again,bake or warm in the microwave.
– Jennifer
Monster Cookie Bars
5 from 2 votes
TheseMonster Cookie Barsare thick, chewy, ultra ooey-gooey, and packed with peanut butter, oats, M&Ms, and three types of chocolate!
Prep Time: 15 minutes
Cook Time: 30 minutes
Yield: 24 bars
Print Pin Rate Recipe
Equipment for this recipe
(equipment shown are affiliate links)
Ingredients
US Customary - Metric
- 1/2 cup unsalted butter melted
- 1 cup dark brown sugar packed
- 1 cup granulated sugar
- 2 cups creamy peanut butter
- 3 large eggs
- 1 tablespoon vanilla extract
- 4 cups old fashioned oats certified gluten free if necessary
- 2 teaspoons baking soda
- 1 teaspoon salt
- 1 cup M&M’s plus more for topping
- 1 cup additional mix-ins plus more for topping (I used equal parts butterscotch chips, chocolate chunks, chocolate chips, and white chocolate chips)
Instructions
Preheat oven to 350 degrees F and grease a 9x13 inch baking dish with cooking spray, then line it with a parchment paper sling.
In the bowl of your stand mixer, beat together melted butter, brown sugar, and granulated sugar until fluffy.
Beat in peanut butter, eggs, and vanilla until combined.
Add in oats, baking soda, and salt, then beat again until incorporated.
Beat in M&Ms and additional mix-ins (butterscotch chips, chocolate chunks/chips, white chocolate chips, etc.).
Pour into prepared pan, then use your hands to press the mixture into an even layer.
Press in extra toppings, if desired (this makes it look pretty).
Bake in preheated oven for 30-40 minutes or until an inserted toothpick comes out basically clean.
Cool completely before removing from the pan, slicing, and serving!
Take 5 seconds to rate this recipe below. We greatly appreciate it!
Rate This Recipe
STORING
Room Temp:1 Week
Refrigerator:2 Weeks
Freezer:3 Months
Reheat:Bake or microwave to warm
*Storage times may vary based on temperature and conditions
People Also Viewed
Cookies
Ice Cream
Cookies
Sweet Things
Cookies
Nutrition Information
Nutrition Facts
Monster Cookie Bars
Amount Per Serving (1 bar)
Calories 333 Calories from Fat 162
% Daily Value*
Fat 18g28%
Saturated Fat 6g38%
Trans Fat 1g
Cholesterol 35mg12%
Sodium 306mg13%
Potassium 211mg6%
Carbohydrates 37g12%
Fiber 3g13%
Sugar 25g28%
Protein 8g16%
Vitamin A 171IU3%
Vitamin C 1mg1%
Calcium 39mg4%
Iron 1mg6%
* Percent Daily Values are based on a 2000 calorie diet.
*Note: Nutrition information is estimated and varies based on products used.
Keywords: easy, m&ms, old fashioned oats
Enjoy this recipe?
Tag @showmetheyummy on Instagram and hashtag it #showmetheyummy
Course: Dessert
Cuisine: American
Author: Jennifer Debth
Reader Interactions
Estella
Bluffton, Indiana
recipe looks great! wondering if i can make these without a mixer and just by hand instead since it conveniently has melted butter. thoughts?
Reply
Jennifer @ Show Me the Yummy
Absolutely! Hope you enjoy 🙂
Anonymous
Williamsport, Pennsylvania
Reply
cheryl
United States
Reply
Di
United States
I would like to make this recipe. Can it be made olive oil instead of butter? I need to lower saturated fat and sugar and thought Splenda/Splenda brown sugar? Also, I have a creamy organic Almond Butter without sodium? Also, dark no sugar added chocolate chips? Thoughts? Thank you.
Reply
Jennifer @ Show Me the Yummy
I don’t recommend olive oil, because of the strong flavor – can you use coconut oil? I’ve never used a sugar alternative like that, but I don’t see why it wouldn’t work. If you look in the post, I don’t recommend all natural nut butters, because I don’t think the bars would hold up as well, but you’re welcome to try! I hope that helps! The chocolate chip sub should be fine. 🙂
Di
United States
Thank you so much for responding! Coconut oil is high in saturated fat and my Dr. would like me to stay with healthy fats like olive, avocado and walnut. I have baked with olive oil before and do not find it has a strong flavor. For me, walnut oil has a very strong flavor. As far as nut butter, maybe I will use half with no sodium and the other with less sodium. Will try and let you know how they turn out.
Jennifer @ Show Me the Yummy
Yes, definitely let us know how they turn out! Hope you enjoy! 🙂
Leave a Comment/Rating
Filter Comments
All Comments 0 Questions 0 Reviews